Last year was a bad year for itch mites. It looks like 2016 may be bad as well. These arthropods are responsible for painful bites that result in itching on people. The mites are barely visible to the naked eye but their bite results in a noticeable raised red area with a centralized blister. It normally takes 10 to 16 hours for itching to start after exposure.
Unlike chigger bites which are usually restricted to areas where clothing is tight such as belts, underwear or socks, oak leaf itch mite bites appear where clothing is loose such as at the neck, shoulder and chest.
Oak leaf itch mites feed on insect larvae living within straw, seeds and plant galls. In recent outbreaks, itch mites have been feeding on midge larvae which cause gall formation on the margins of certain oak leaves. Pin oaks are most likely affected but red oaks and black oaks can also act as a host for the midges. The female mite is able to enter the gall through small openings and paralyze the midge larvae with a neurotoxin. The midge then acts as a food source for the mite allowing her to develop about 200 offspring. It takes about a week for the new mites to emerge. Only about 5 to 10 percent of the progeny are males. The males do not feed but mate and then die. Females seek new hosts on the existing tree but can be carried by winds for hundred of yards. Mite populations appear in late July and continue through the summer and into the fall.
No effective control has been found. Deet-based repellents have not given consistent results. Tree sprays are ineffective as the mites are protected by the galls. Oak trees known to be infested with mites should be avoided. If work must be done near oak trees with marginal leaf gall, bathing and changing and washing clothing is recommended. This article was adapted from our publication MF2806, “Oak Leaf Itch Mite.” (Ward Upham)